The control of multidrug-resistant tuberculosis has been hampered by the lack of rapid methods for antimicrobial susceptibility testing. This SBIR program is designed to provide a novel approach to rapid antibiotic susceptibility testing, based on One Cell Systems proprietary gel microdrp (GMD) encapsulation technology. In Phase I, encapsulation of M. bovis and smegmatis was used as a model system to evaluate analysis of growth in GMDs. After culture for 1-4 days, and fluorescent staining of the GMDs with auramine, automated analysis of GMDs by flow cytometry could be used to quantify clonal growth and susceptibility to antibiotics. Furthermore, the presence of a 3% antibiotic-resistant population could be detected. In Phase II, the research is designed to increase the detection sensitivity to 1% resistance and evaluate this technology using clinical samples. These experiments will form the basis for a commercially viable, rapid mycobacterial growth and susceptibility assay. The re-emergence of tuberculosis as a public health problem in the United States points tot he urgent need for rapid detection methods. PROPOSED COMMERCIAL APPLICATION: A method for the rapid assessment of mycobacterial growth and antimicrobial susceptibility will be developed. Such a method will reduce health care costs by allowing faster interventional drug therapy. This GMD technique can also be adapted for rapid susceptibility determinations for other infectious diseases.